Recent developments in functional organic polymer coatings for biomedical applications in implanted devices

Organic polymer coatings have been commonly used in biomedical field,which play an important role in achieving biological antifouling,drug delivery,and bacteriostasis.With the continuous development of polymer science,organic polymer coatings can be designed with complex and advanced functions,which is conducive to the construction of biomedical materials with different performances.According to different physical and chemical properties of materials,biomedical organic polymer coating materials are classified into zwitterionic polymers,non-ionic polymers,and biomacromolecules.The strategies of combining coatings with substrates include physical adsorption,chemical grafting,and self-adhesion.Though the coating materials and construction methods are different,many biomedical polymer coatings have been developed to achieve excellent performances,i.e.,enhanced lubrication,anti-inflammation,antifouling,antibacterial,drug release,anti-encrustation,anti-thrombosis,etc.Consequently,a large number of biomedical polymer coatings have been used in artificial lungs,ureteral stent,vascular flow diverter,and artificial joints.In this review,we summarize different types,properties,construction methods,biological functions,and clinical applications of biomedical organic polymer coatings,and prospect future direction for development of organic polymer coatings in biomedical field.It is anticipated that this review can be useful for the design and synthesis of functional organic polymer coatings with various biomedical purposes.

Supramolecular self-assembled nanoparticles for targeted therapy of myocardial infarction by enhancing cardiomyocyte mitophagy

Myocardial infarction accompanied by diabetes mellitus is accepted as the most seri-ous type of coronary heart disease,and among the current treatment strategies,the precise delivery of protective drugs for inhibiting cardiomyocyte apoptosis is still a challenge.In this study,we developed a biodegradable nanoparticles-based delivery system with excellent macrophage escape,cardiac targeting,and drug release prop-erties to achieve targeted therapy of myocardial infarction.Specifically,a copolymer of p(DMA–MPC–CD)combining self-adhesion,hydration lubrication,and targeting peptide binding site was successfully prepared by free radical copolymerization,and it was self-assembled on the surface of melatonin-loaded dendritic mesoporous silica nanoparticles(bMSNs)following the integration of adamantane-modified cardiac homing peptide(CHP)based on supramolecular host–guest interaction.Importantly,a hydration layer formed around the zwitterionic phosphorylcholine groups of the multifunctional nanoparticles,which was confirmed by the enhancement in hydra-tion lubrication and reduction in coefficient of friction,prevented the nanoparticles from phagocytosis by the macrophages.The in vivo bioluminescence imaging test indicated that the nanoparticles were endowed with satisfied cardiac targeting capa-bility,and the in vivo mice study demonstrated that the intravenous injection of drug-loaded nanoparticles(namely bMSNs–Mel@PDMC–CHP)effectively reduced cardiomyocyte apoptosis,alleviated myocardial interstitialfibrosis,and enhanced cardiac function.

Biomimetic injectable hydrogel microspheres with enhanced lubrication and controllable drug release for the treatment of osteoarthritis

The occurrence of osteoarthritis(OA)is highly associated with the reduced lubrication property of the joint,where a progressive and irreversible damage of the articular cartilage and consecutive inflammatory response dominate the mechanism.In this study,bioinspired by the super-lubrication property of cartilage and catecholamine chemistry of mussel,we successfully developed injectable hydrogel microspheres with enhanced lubrication and controllable drug release for OA treatment.Particularly,the lubricating microspheres(GelMA@DMA-MPC)were fabricated by dip coating a self-adhesive polymer(DMA-MPC,synthesized by free radical copolymerization)on superficial surface of photo-crosslinked methacrylate gelatin hydrogel microspheres(GelMA,prepared via microfluidic technology),and encapsulated with an anti-inflammatory drug of diclofenac sodium(DS)to achieve the dual-functional performance.The tribological test and drug release test showed the enhanced lubrication and sustained drug release of the GelMA@DMA-MPC microspheres.In addition,the functionalized microspheres were intra-articularly injected into the rat knee joint with an OA model,and the biological tests including qRT-PCR,immunofluorescence staining assay,X-ray radiography and histological staining assay all revealed that the biocompatible microspheres provided significant therapeutic effect against the development of OA.In summary,the injectable hydrogel microspheres developed herein greatly improved lubrication and achieved sustained local drug release,therefore representing a facile and promising technique for the treatment of OA.

Self-adhesive lubricated coating for enhanced bacterial resistance

Limited surface lubrication and bacterial biofilm formation pose great challenges to biomedical implants.Although hydrophilic lubricated coatings and bacterial resistance coatings have been reported,the harsh and tedious synthesis greatly compromises their application,and more importantly,the bacterial resistance property has seldom been investigated in combination with the lubrication property.In this study,bioinspired by the performances of mussel and articular cartilage,we successfully synthesized self-adhesive lubricated coating and simultaneously achieved optimal lubrication and bacterial resistance properties.Additionally,we reported the mechanism of bacterial resistance on the nanoscale by studying the adhesion interactions between biomimetic coating and hydrophilic/hydrophobic tip or living bacteria via atomic force microscopy.In summary,the self-adhesive lubricated coating can effectively enhance lubrication and bacterial resistance performances based on hydration lubrication and hydration repulsion,and represent a universal and facial strategy for surface functionalization of biomedical implants.

Polymeric coating lubricates nanocontainers to escape macrophage uptake for bioreceptor recognition

Accurate drug delivery to the lesion has been deliberated for several decades,but one important phenomenon is usually neglected that the immune system can prevent smooth transportation of nanomedicine.Although injection would reduce first-pass effect,macrophages in the blood can still recognize and phagocytose nanomedicine.Here we show that a lubricated nanocontainer,which is prepared based on polyelectrolytes and mesoporous silica nanoparticles,can accurately target muscarinic bioreceptor while escaping from the identification of macrophages.Through in vitro and in vivo studies,this nanocontainer,combining both immune escape and bioreceptor targeting,has greatly improved the drug bioavailability.Additionally,this nanocontainer shows good biocompatibility,and the targeted heart tissues and other important metabolic organs,such as liver and kidney,keep physiological structures and functions without the detection of side effects.Furthermore,the mechanism of immune escape for the developed nanocontainer has been investigated by lubrication test and molecular simulation.We anticipate that our study will establish a new perspective on the achievement of immune escape-based targeted drug delivery,which can provide a fundamental approach for the design of related biomaterials.